Scientific evidence indicates that physical activity contributes in important ways to the improved health, functioning. and quality of life of older adults, which in turn enhance independence and contribute to reduced utilization of health care. A critical next step is to increase the physical activity levels of large segments of the older adult population, who are largely sedentary. This requires community-based, public-health oriented programs appropriate for all older adults as well as recruitment strategies that effectively recruit those who can most benefit yet who typically do not volunteer to join such programs. The Community Healthy Activities Model Program for Seniors (CHAMPS) is among the first of such programs attempting to fill these needs, encouraging enrollees to participate in community-offered physical activity classes and programs. CHAMPS successfully increased physical activity levels in a sizeable proportion of enrollees over a 6-month period; those who did so experienced corresponding improvements in psychological well-being. Based on the results from this first-generation project, we propose to extend and improve the recruitment methods and the intervention. The specific aims are to: (1) implement, using a randomized, controlled design, a 1- year community-based intervention that is tailored to individual needs and preferences, combines use of physical activity classes offered by the community with home-based approaches, and targets underactive older adults (65+ years of age) enrolled in a Medicare HMO; (2) evaluate the effectiveness of the program in terms of increased physical activity levels, enhanced physical functioning and other aspects of health-related quality of life; (3) identify factors contributing to program adoption and refusal; (4) describe the effectiveness of innovative recruitment methods to reach those who can most benefit; and (5) evaluate cost-effectiveness. The emphasis is on increasing moderate-intensity endurance activities such as walking, swimming, and general conditioning exercises that expend calories and promote leg strength that are important to physical functioning, and that are relatively easy for seniors to participate in. Using principles of social cognitive and stages of change theories, each person will be encouraged to begin at his/her own level and gradually increase the frequency and duration of activity, aiming for a goal of 3-4 times weekly. Approximately 1,100 HMO enrollees will be screened by telephone and enumerated. Eligible persons will be proactively recruited using innovative methods to attend an introductory meeting where they will be invited to join. Of these, 240 will be randomized and followed for a 1- year period; the wait-list control group will receive the program at that time. Results will be evaluated using analysis of covariance and other multivariate methods. The goal of the study is to facilitate long-term lifestyle changes in physical activity patterns by developing a program that meets the needs of as many seniors as possible and can ultimately be integrated into a local senior center or a Medicare HMO as an ongoing service to older adults in the community.